Slime-pulp thickener



C. ALLEN.

SLIME PULP THICKENER. APPLICATION map o cr.10. 1918.

1,360 ,703. Patented Nov. 30, 1920.

fnueflfar' Chariw/f'llen. 29

.JttaMg/u UNITED STATES PATENT OFFICE.

-CHA RLES ALLEN, OF EL PASO, TEXAS.

Specification of Letters Patent. Patent d N 19 0 Original application filed June 9, 1917, Serial No. 173,785. Divided and this application filed October 10, i 1918. Serial No. 257,623.

To all whom it may concern:

Be it known that I, CHARLns ALLEN, a citizen of the United States,residing at El Paso, in the county of El Paso and State of Texas,

have invented new and useful Improvements in Slime-Pulp Thickeners, of which the following is a specification.

This invention relates to a device for 1 most universally used in the treatment of ores by wet milling processes,and in its every application it is of prime importance that the degree of thickening be uniform; that is, that the discharge of the thickened slime be always of the same density. Thickeners heretofore used depend upon the volume of pulp fed to the cone or'tank for regu lation of the size of the discharge orifice.

' The results are very unsatisfactory, inasmuch as the proportion :ofliquids to solids in the material discharged varies with the volume of slime pulp fed to the thickener.

In the present invention, the volume of slime pulp in the thickener in no manner alters the proportion of liquids to solids in the products discharged,within the limits of the capacity of the machine; The degree of thickening'is controlled, and for Whatever degree of thickening the device is adjusted, that degree of thickening is automatically maintained.

In slime pulp, the finely divided solids move freely without appreciably affecting the fluidity by friction among themselves;

Such a pulp has the properties of a liquid so lon h en the pulp is composed of water and solid particles of greater specific gravity than water, the specific gravity of the pulp increases with all increasesin the'quantity of solids in suspension' in the pulp; This pulp may therefore be considered as a liquid of greater density than water. 7 a g In, my invention I employ what may be termed two compartments having in one compartment a liquid, and in the other a mixture of liquid and solids or pulp. These compartments are so arranged that the variations in the density of the carrying off the thickened product.

as the solids are kept in suspension. f

pulp, due to the presence of more orvless solids in suspension, act to ralse and lower the column of liquid, which column of liquid carries a float operatlvely connected to avalve at the bottom of the tank controlling the discharge orifice. lVhenthe pulp attains a certain density the valve is automatically opened to permit the discharge of the thickened pulp through the bottom orifice, and when the density of the pulp falls below a critical point, the valve is automatically operated to close the orifice.

Hence the degree of thickening of the pulp discharged through the automatically controlled orifice is practically the same under all conditions or variations in the volume of slime pulp fed into the tank. The volume of thickened slime discharged through the orifice may Vary considerably, but the density of'the thickened slime discharged remams practically constant. This is the reverse of the thickeners ordinarily used in which the volume of thickened slime discharge remains constant while the density of the discharge varies with the quantity fed into the thickener.

The invention is illustrated by way of example in the accompanying drawing in which the figure discloses the complete apparatus, as seen in central, vertical section. Referring more particularly to the drawmg, the apparatus isshown as comprising a tank 10 in the shape of an inverted cone havinga' discharge orifice 11 at its bottom for A launder 12 is arranged around the top of the tank for carrying ofi? clear liquid which overflows the rim of the tank. A conduit 13 is provided to supply slime pulp to the center of the tank. The outlet 11 of the tank is indirectly aflected by a, float 14 having variable buoyancy due to the application of adjustable weights 15. This float is provided with operable connections 16 which extend downwardly and engage the mechanism of a valve 1.7 controlling the discharge orifice 11. In the present instance the float is circular, being positioned within an annular chamber 18 which has outer and inner concentrically spaced walls forming the float chamber, at

the same time separating it from a central,

vertical opening through which the pulp passes to the tank from the conduit 13. The float chamber 18 is of suflicient height to ex tend to a level considerably above that of the rim of-the tank and further extends downwardly to a level below the rim of the tank. This chamber is supplied with clear water through an inlet supply pipe 22.

The float chamber is providedwitha series of connecting elements 20 which extend downwardly from the lower tapered wall thereof. The lower ends are in conununica tion W-ith arubber or other fiexiblebag .23. This bag is filled with clear'water adapted to pass into the fioatchamber 18 through the openings '20. The fluid in the bag does not come incontac't with the' m'aterial in the tank and hence it i impossible for the clear water to become containinated. Due

to the fact that the bag is of flexible mate rial and thatthere sa difference in density.-

of the contents of the tank around the bag and the contents of the'bag and the superimposed column in chamber 18 it 1s. possible for the float let tobe actuated and thus.

to regulatethedischarge valve at thebottom of 'the tank. l

.' It will be readily understood that the slime which thickenswithin the tank will :at

the same' 'time increase in weightand will therefore increase the external pressure, on

the bag to contract the same; and raise the level of the water inl the fioat chambein The contraction will takeplace until hydroi 'static balance is produced between the, liquid within the bag and the surrounding liquid within the tank. It will be evident that the ac'tion'of the two liquids to produce a hydrostatic balance would be the same as though there was no membrane interposedbetween them. In this instance,however,"the clear water Wlll be protected. It is also obvious that any other medium sensitive to the diflerent pressures caused bythe increase or decrease in the densityof the slime pulp, such as afree working sleeve or a mercury seal, could be used instead of the bag with equally desirable results, the working sleeve liftingthe pulp in the fioat chamber bodily I while the action of the mercury seal would be similar to the action of the bag.

By analysis it will be seen that 'thefloat chamber 18 and the bag23 constitute one of the compartments before referred to an'd the "tankan'd its .pulp forms the. other, .These two compartments are so arranged as to stand in hydrostatic balance in relation to each other as permitted by the flexibility of thefbag. The variation in the density of the pulp outside the bag 23 will act to vary the.

heightof the column of water within the chamber and-will thereby directly produce a raising or lowering of the float and through this action open or. close the dischargeorifice.

In the present instance, 'the actuating force is the difiierence in the density of the contents'ofthe andthe chamber 18,. which, to "maintain a hydrostatic balance,

raises the surface of the'liquid in the coinpartment containing the liquid of lesser density abovexthe level of the surface in the compartment containing the -material of greater density. This difference of level is directly proportionate to the difference in the densities of the liquid. 7 If it is assumed that the tank is filled with water as well as 'the bag 23 and the column 18, the vertical length of the columns would. be the same;

that is, the level of their surfaces would be the same. If, without altering the length of the column, the density of the contents of one liquid column of theapparatus, is increased my, one-tenth. Then to inaintaiu a hydrostatic balance, the length of the opposing column must be increased one-tenth. Applying this to the device here shown, the

proportion of-the tank 10 above the loi r ance between. the" two columns, the water level in the float chamber will, of necessity. be h gherthan; the level of the thickened slime, in the tank anc'lv directly in proportion to the excess'in density of the contents of the tank over that of the contents of the float chamber and its associated'parts.

rissumin'g this difference in the density of the liquids in the two columnsto be and r the lengthofthe both columns when OCCllf pied byla liquid of the same density, to be 25 inches. 1 Then the differencein the length of the two columnswould'be 6.25 inches. To prepare the device for operatiornthe bag 23 and thechamber 18 are filled with clear water to a predetermined height in the chamber. Slime pulp is then admitted to the tank through the. conduit 13 and as the liquid contents of thetank thereafter overflows the rim tl1ereof,the thickening process will take place.

It will'thus .be seenthat an apparatus is here provided which will auton1atically op-' crate to inaintainthe slime at a uniform density, said operation being dependent upon desire to secure byLetters Pat- I like, a settling tank having a controllable orifice for the discharge of the heavier and more quickly settling particles, and an overflow rim for the lighter and more slowly settling particles, afluid column of fixed density in operative relation to the material to be thickened and affected by variations in the density of said material to cause a change in the elevation of the fluid column, means to prevent the material in the tank from entering the fluid column, and means actuated by the rise and fall of the fluid column to control the size of the discharge orifice in the tank.

2. A thickener for slime pulp compris ing a tank, and a discharge orifice for the discharge of the settled material contained therein, a fluid compartment having flexible walls disposed within said tank and adapted to register the variations of pres sure caused by the change in the density of settled material surrounding the compartment by the raising and the lowering of the fluid contained therein, a float in said fluid compartment, and connecting means between said float and discharge orifice whereby settled material of a certain density is automatically discharged.

3. A thickener for slime pulp comprising a tank having a discharge orifice for the dis-' charge of settled material, a'bag made from flexible material disposed within said tank, float chamber disposed above said bag and having communication therewith, said bag being adapted to register the change in pressure due to the change in density of the surrounding material by raising and lowerin 'the level of the fluid within said float chamber, a float within said chamber and operating connections between the float and the discharge orifice whereby settled material of a certain density is discharged automatically.

4. A thickener for slime pulp comprising a tank having a discharge orifice adapted for the discharge of settled material therein, a fluid compartment having flexible walls disposed within said tank, a float chamber above said compartment and in communication therewith, the fluid having a predetermined height in said float chamber, adapted to give a hydrostatic balance between the column of fluid in said compartment and float chamber and the liquid in the tank, a float in said chamber and connecting means between said float and controllable orifice whereby settled material of a predetermined density is discharged. 4

5. A thickener for slime pulp comprising a tank having a discharge orifice for thickening material in the bottom thereof, a fluid compartment having flexible walls disposed within said tank, a float chamber disposed above said compartment and in communication therewith, a float in said chamber whereby the change in pressure, due to the variation in the density of the pulp surrounding said compartment, is registered, adjustable means for regulating the buoyancy of the float, and means for connecting said float with a discharge orifice whereby the discharge-of liquid of a predetermined density is had.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

CHARLES ALLEN.

Witnesses J. L. ELY,

EDMUND SHAW. 

